Antibiotic-resistant bacteria: Who is winning the battle?

Physicians and clinicians face an ongoing challenge: to keep up with increasingly stubborn, resistant bacteria that cause significant infections. The more exposure bacteria have to our available antibiotics, the higher their chances of evolution into a resistant form, with serious effects on medical care.

The heavy use of antibiotics, from hand soap ingredients to prescriptions, for conditions that won’t even respond to an antibiotic is fostering the proliferation of these heavy-duty bugs. Over the past 10 years, the number of resistant bacteria has proliferated at an alarming rate.

One mechanism of response is to reduce the overuse of antibiotics in general — something we can all help with, in the interest of more appropriate treatment and the health of the environment.

Another important approach is to make sure the antibiotics used are the ones most effective in killing the bacteria causing the infection. A targeted antibiotic that does the job right and knocks out all the bacteria stops that organism’s opportunity to learn and evolve into a stronger form that poses a more serious health risk.

And how do we learn which ones work best? That’s where the microbiology testing by associate professor Mark Garrison, pharmacotherapy, comes in.

Garrison received a 2004 WSU Spokane seed grant for his study of a new investigational agent called tigecycline. Early-stage testing indicates that the drug may be effective against certain forms of resistant bacteria, but more information is needed to compare it with established medications.

Traditional in vitro susceptibility testing methods are limited, in that bacterial isolates being tested are exposed to static concentrations of antimicrobials. In an actual patient (in vivo), concentrations of antimicrobials achieve a peak concentration within the body and gradually decline over time based on their pharmacokinetic properties.

Garrison uses a mechanical glass model known as an in vitro pharmacodynamic modeling apparatus (PDM). The PDM was specifically developed to determine how well an antibiotic can kill bacteria over time by simulating the concentrations of antibiotic one would expect if a dosage of the antibiotic were given to an actual patient.

Only a limited number of investigators utilize this methodology, making the PDM an innovative and important research tool. According to Garrison, one of the original designers of the model, it requires custom fabrication by a glass blower. Around the world, around a dozen or so researchers publish investigations of antibiotic action based on use of the model.

In his research, Garrison will use the mechanical model to compare the activities of tigecycline and other antibiotics frequently used to treat infections involving resistant bacteria.

The central purpose of the WSU Spokane faculty seed grant program is to encourage faculty to develop research programs in Spokane that have the potential for extramural support, in particular from significant federal agencies. Their research will provide preliminary data to support applications for such funding.